The invention relates to a semiconductor device provided with an insulating substrate and a conductive mounting surface, said insulating substrate being provided on a conductive ground surface. A bipolar transistor is provided on the mounting surface with a first main surface of the transistor in contact with the mounting surface, and the transistor is provided with connection pads for an emitter, base, and collector.
Such a device is particularly suitable for high-frequency applications, especially for modules provided with transmitter transistors. Such modules comprise an insulating substrate, for example made from a ceramic material, on which conductive mounting surfaces are provided with components thereon such as transistors, diodes, resistors, capacitors, etc. Such semiconductor devices are also known as thin or thick film circuits. The insulating substrates are mounted against a conductive ground surface, for example a heat sink, printed circuit board, screening, or housing.
A device of the kind mentioned in the opening paragraph is known from the English abstract of Japanese Patent Application no. 6-260563. The transistor in this known device is soldered to the conductive mounting surface with its first main surface, which at the same time serves as a connection surface for the collector, the conductive mounting surface thus acting as the collector connection of the transistor. The conductive mounting surface is for this purpose connected to further components by means of a bonding wire. To prevent flowing-out of solder on the conductive mounting surface while the transistor is being provided, this conductive mounting surface is provided with a groove in which the transistor is soldered. The conductive mounting surface may then be chosen to be comparatively small, so that the high-frequency properties of the transistor are good.
The known device described has the disadvantage that the high-frequency properties of the transistor are not good enough for some applications. In addition, the known device is difficult to manufacture on account of the groove in the mounting surface.